System and method improving satellite capability through power sharing

ABSTRACT

In accordance with various embodiments of the disclosed subject matter, a system and method is configured for scheduling and invoking power sharing among satellites within a constellation of satellites such that energy storage systems at a target satellite may by charged prior to the use of electric propulsion thrust activation or other high electricity demand operations (or such operations contemporaneously augmented) by power beams transmitted from other (source) satellites within the constellation.

GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or forthe Government of the United States for all governmental purposeswithout the payment of any royalty.

FIELD OF THE DISCLOSURE

The present disclosure relates to satellite systems in general and, moreparticularly, to systems and method for improving the capability ofsatellites within a constellation of satellites by sharing power therebetween.

BACKGROUND

It is well known that electric propulsion for spacecraft offerssubstantial mass savings (reduced propellant) compared to chemicalpropulsion based systems to achieve the same change in spacecraftvelocity. Because of this advantage, electric propulsion has beenadopted and applied to spacecraft by multiple entities. However, thereis a major disadvantage of electric propulsion, which is the fact thatthe outstanding propellant efficiency comes at the price ofsubstantially lower spacecraft acceleration than can be achieved withchemical propulsion. The lower spacecraft acceleration capabilityincreases the time to achieve desired changes in orbital velocity (orbitchanges), which can be unpalatable for certain operational requirements.

The spacecraft acceleration produced by electric propulsion has a directfunctional relationship to the spacecraft specific power (defined as theratio of the electric power applied to the electric thruster divided bythe total spacecraft mass). Therefore, if one can conceive of amethodology to increase the spacecraft specific power of an electricpropulsion driven spacecraft, one can increase the spacecraftacceleration produced by the electric propulsion. Increasing thespacecraft acceleration then decreases the time to achieve a prescribedchange in spacecraft velocity. The old method of applying electricpropulsion generally limits the source of the power being supplied tothe electric propulsion system to that which is generated onboard thethrusting satellite. This approach severely limits the satelliteacceleration that can be achieved using electric propulsion, whichcauses orbit changes to be very slow. The current invention provides amethodology to substantially increase the spacecraft specific power suchthat the major disadvantage of electric propulsion, which is lowacceleration, is markedly overcome.

SUMMARY OF THE INVENTION

Various deficiencies in the prior art are addressed below by thedisclosed systems, methods, architectures, mechanisms, apparatus and thelike for scheduling and invoking power sharing among satellites within aconstellation of satellites such that a target satellite maycontemporaneously use the received power to augment power supplied toelectric propulsion thrusters, or any other high electricity demandoperations. Alternatively, the target satellite can store the receivedenergy, or portions thereof, in onboard energy storage systems to meetfuture expected power needs.

A system according to one embodiment comprises a constellation of earthorbiting satellites; wherein at least some of the satellites include anelectric-driven propulsion (EP) system and a power receiver configuredto convert received power beams into electricity for use by the EPsystem; wherein at least a some of the satellites include a powertransmitter configured to generate a power beam and transmit thegenerated power beam toward a target satellite; wherein an orbitalmaneuver of a target satellite is supported by one or more satellitestransmitting power beams toward the target satellite while the targetsatellite activates its EP system to generate thrust and its powerreceiver to generate electricity to augment the ability of the EP systemto generate thrust. The EP systems may be sized to necessitate thegeneration of augmented thrust via received power beams; theconstellation of earth orbiting satellites comprises a plurality ofsatellites of similar power level; the power beams comprise laser powerbeams, and the power receivers comprise photovoltaic systems; the powerbeams comprise microwave power beams, and the power receivers compriserectennas. A power beam schedule may be determined for each targetsatellite prior to a respective scheduled EP thrust activation or otherhigh electricity demand operation, the power beam schedule identifyingfor each target satellite one or more power sourcing satellites toprovide power for the target satellite, and one or more predeterminedtime periods for each of the power sourcing satellites to provide powerto the target satellite. Other modifications are contemplated.

A satellite according to an embodiment may comprise an electric-drivenpropulsion (EP) system configured to generate thrust; a power receiverconfigured to convert received power beams into electricity foraugmenting thrust generated by the EP system; and a controller,configured to synchronize an orbital maneuver of the satellite utilizingthrust generated by the EP system to a receiving of one or more powerbeams; wherein the satellite is included within a constellation ofsatellites orbiting the earth, and the one or more power beams receivedfrom one or more power sourcing satellites within a constellation ofsatellites; and wherein power beams are received in accordance with apower beam schedule determined prior to a scheduled EP thrustactivation, the power beam schedule identifying the one or more powersourcing satellites and one or more predetermined time periods for eachof the power sourcing satellites to provide power. Other modificationsare contemplated.

Additional objects, advantages, and novel features of the invention willbe set forth in the description which follows, and will become apparentto those skilled in the art upon examination of the following or may belearned by practice of the invention. The objects and advantages of theinvention may be realized and attained by means of the instrumentalitiesand combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentinvention and, together with a general description of the inventiongiven above, and the detailed description of the embodiments givenbelow, serve to explain the principles of the present invention.

FIG. 1 graphically depicts a satellite constellation benefitting fromvarious embodiments;

FIG. 2 depicts a simplified block diagram of a satellite according to anembodiment;

FIG. 3 depicts a method according to an embodiment;

FIGS. 4-5 graphically depicts advantages that may be achieved inaccordance with the various embodiments;

FIG. 6 depicts a high-level block diagram of a computing device suitablefor use within the context of the various embodiments.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the sequence of operations as disclosedherein, including, for example, specific dimensions, orientations,locations, and shapes of various illustrated components, will bedetermined in part by the particular intended application and useenvironment. Certain features of the illustrated embodiments have beenenlarged or distorted relative to others to facilitate visualization andclear understanding. In particular, thin features may be thickened, forexample, for clarity or illustration.

DETAILED DESCRIPTION OF THE INVENTION

The following description and drawings merely illustrate the principlesof the invention. It will thus be appreciated that those skilled in theart will be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of theinvention and are included within its scope. Furthermore, all examplesrecited herein are principally intended expressly to be only forillustrative purposes to aid the reader in understanding the principlesof the invention and the concepts contributed by the inventors tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions. Additionally, theterm, “or,” as used herein, refers to a non-exclusive or, unlessotherwise indicated (e.g., “or else” or “or in the alternative”). Also,the various embodiments described herein are not necessarily mutuallyexclusive, as some embodiments can be combined with one or more otherembodiments to form new embodiments.

The numerous innovative teachings of the present application will bedescribed with particular reference to the presently preferred exemplaryembodiments. However, it should be understood that this class ofembodiments provides only a few examples of the many advantageous usesof the innovative teachings herein. In general, statements made in thespecification of the present application do not necessarily limit any ofthe various claimed inventions. Moreover, some statements may apply tosome inventive features but not to others. Those skilled in the art andinformed by the teachings herein will realize that the invention is alsoapplicable to various other technical areas or embodiments.

Various embodiments improve the capability (e.g., maneuverability) ofsatellites within a constellation of satellites so as to maximize thevalue of the constellation of satellites. For example, variousembodiments contemplate optimizing energy storage and propellant useassociated with electric driven propulsion systems for a targetsatellite by directing power to the target satellite from other (source)satellites in the constellation. In this manner improvedcapability/maneuverability (e.g., total velocity change, and propellantuse efficiency) of a constellation of satellites is provided to increaseutility of a satellite constellation by enabling more frequent,advantageous positioning of individual satellites in the constellationto maximize performance metrics (e.g. ground observation coverage,communication and broadcast coverage); extend constellation lifetime byincreasing total velocity change capability of the constellation; andreduce launch cost, and secure easier space access by lowering totalsatellite mass (lower propellant mass needed to achieve operationalrequirements)

Various embodiments discussed herein comprise, illustratively, systems,methods, architectures, mechanisms, apparatus, computer implementedmethods and/or frameworks configured for, illustratively, increasing theratio of total delta velocity change capability to propellant mass of asystem comprising of a plurality of earth orbiting satellites in aconstellation, such as a plurality of satellites of comparable sizes andpower levels where each satellite is equipped with power transmitcapability (e.g. laser, microwave) and power receive capabilitycompatible with its transmit capability (e.g. photovoltaics, rectennas),and an electric-driven propulsion system (e.g. Hall Effect, Ion,Electrospray, etc.).

By periodically transmitting power from other satellites in theconstellation to a target satellite within the constellation, atemporary step increase in the ratio of satellite power per totalsatellite mass is enabled; that is, the target satellite may operate itselectric propulsion subsystem while receiving transmitted (augmented)power to enable increased efficiency of propellant use (high deltavelocity to propellant mass ratio) by its onboard electric propulsionsystem. Further, various embodiments provide a mechanism for increasingspacecraft accelerating (thrust) capability at a fixed specific impulseof an electric-driven propulsion system (e.g. Hall Effect, Ion, etc.)installed on a satellite within the constellation.

FIG. 1 graphically depicts a satellite constellation benefitting fromvarious embodiments. Specifically, FIG. 1 depicts a constellation 100 ofsatellites 110 orbiting the Earth 105, wherein each satellite 110 withinthe constellation 100 of satellites is equipped with an electric-drivenpropulsion (EP) system configured for generating thrust sufficient tomove the satellite within the constellation satellites, a powertransmitting system configured to beam or transmit power toward othersatellites 110 and a power receiving system configured to receive powertransmitted or beamed from other satellites 110 (i.e., satellites 110are configured to share power with each other).

The power transmitting and receiving systems may be configured totransmit/receive laser energy/power, microwave energy/power and thelike. In the case of laser power, each satellite in the constellation isequipped with a power transmitting system comprising one or more laserscapable of generating laser power and directing that laser power towardanother satellite in the constellation, as well as a power receivingsystem comprising photovoltaic devices configured to efficiently receiveincident laser power from multiple other satellites in the constellationand convert this into electrical power. In the case of microwave power,each satellite in the constellation is equipped with a powertransmitting system comprising microwave transmitters capable ofgenerating microwave power and directing that microwave power towardanother satellite in the constellation, as well as a power receivingsystem comprising a microwave receiver (e.g., a rectenna) configured toefficiently receive incident microwaves from multiple other satellitesin the constellation and turn this into electric power.

Referring to FIG. 1 , a first satellite 110-1 is depicted as receivingpower (e.g., laser, microwaves and the like as indicated by the arrows)transmitted from each of a first plurality of power transmittingsatellites 110-101 through 110-113, and a second satellite 110-2 isdepicted as receiving power transmitted from each of a second pluralityof power transmitting satellites 110-201 through 110-211. Thus, at theparticular moment in time represented by the operation depicted in FIG.1 , the first 110-1 and second 110-2 satellites are receiving power fromrespective groups of satellites such that enhanced thrust via therespective electric propulsion systems may be utilized. That is, a powertransfer process between satellites is provided wherein, illustratively,based on the number of satellites in the constellation and missionparameters, each satellite would take its turn receiving power frommultiple other satellites in the constellation such that its spacecraftspecific power (power delivered to electric-driven thrusters divided byspacecraft total mass, W/kg) would experience a substantial stepincrease.

The various embodiments are not simply satellite to satellite powerbeaming per se, but a mechanism of equipping an entire constellation ofsatellites with power beaming and receiving capability to share poweramong members of a constellation of satellites in conjunction withelectric propulsion. One aspect of the embodiments described herein isimplementing the power beaming in a constellation of similarly sizedsatellites that are all equipped with power transfer capability andelectric propulsion.

Generally speaking, power transmitting satellites are configured totransmit power to a target satellite contemporaneously with the targetsatellite requiring augmented thrust from its electric-driven propulsionsystem such as to perform an orbital maneuver of some type. In otherscenarios, power transmitting satellites are configured to transmitpower to a target satellite to increase and/or maximize target satelliteenergy storage levels (e.g., battery charge levels, super capacitors,flywheels etc.) prior to and/or during target satellite use of its EPsystem or other high electricity demand operations (e.g., such asoperating a power-hungry payload and the like). In various embodiments,beamed power may coordinated for use in augmenting various spacecraftactivities such as communications, data processing, energy storage andthe like. In various embodiments, received beamed power may be directlyconverted into thermal energy (e.g., such as for thermal rocketpropulsion).

As discussed below with respect to FIG. 3 , in various embodiments apower beam schedule may be determined for a target satellite prior to ascheduled high electricity demand operation by the target satellite, thepower beam schedule comprising at least an identification of powersourcing satellites selected to provide power for the target satelliteat one or more predetermined times and an amount of power to be providedby the power sourcing satellites during the predetermined times. Thepredetermined times may comprise pre-operational time periods duringwhich target satellite energy storage levels are increased via receivedpower beam(s), operational time periods during which target satellitepower used for high electricity demand operations is augmented bycontemporaneously received power beans(s), and/or post-operational timeperiods during which target satellite energy storage levels are restoredor otherwise replenished via received power beam(s).

FIG. 2 depicts a simplified block diagram of a satellite according to anembodiment. Specifically, FIG. 2 depicts a satellite 200 suitable foruse as any of the satellites 110 described above with respect to FIG. 1.

The satellite 200 of FIG. 2 is depicted as including a payload and mainfunctions 210, controller 220, batteries 230, and electric-drivenpropulsion (EP) system 240, a power receiver module 250, a powertransmitter module 260, a Power Management and Distribution (PMAD)system and a solar array 280.

The payload main functions 210 comprise the normal payload of theparticular satellite, the main control and telemetry functions of thesatellite and so on. The controller 220 may be included within thepayload and main functions 210 or may be independent as depicted.Generally speaking, the controller 220 includes control circuitrynecessary to perform the various tasks described herein with respect tothe embodiments. The controller 220 may be implemented as a specialpurpose or general purpose computing device, such as depicted below withrespect to FIG. 6 .

The energy storage system (e.g. batteries) 230 comprise the primaryelectric source of the satellite and may be recharged via photovoltaicarrays 280 configured to capture solar radiation and the like as isknown (e.g., routed directly or via the PMAD 270). The energy storagesystem 230 may also be configured to be recharged via energy/powerreceived from the power receiver module 250 directly and/or via the PMAD270. The energy storage system 230 provides energy/power to the powertransmitter module 260 directly or via the PMAD 270. The solar array mayprovide energy/power to the power transmitter module 260 directly or viathe PMAD 270.

The electric-driven propulsion (EP) system 240 generally comprises asystem capable of generating some or all of the thrust necessary to movethe satellite within the constellation of satellites. The EP system 240may comprise any electric-driven space propulsion technology, whichgenerally falls into three categories; namely, electrothermal,electrostatic, and electromagnetic. Suitable electric-driven spacepropulsion technologies include, illustratively, Hall Effect thrusters,gridded ion engines, high efficiency multistage plasma thrusters, pulsedplasma thrusters, resistojets, arcjets, field emission electricpropulsion thrusters, electrospray/field emission thrusters,magnetoplasmadynamic thrusters and so on. Depending upon the EP systemutilized, a variety of propellants can be used (e.g. xenon, iodine,etc.).

Various embodiments contemplate that power may be transferred fromsatellite to satellite within a satellite constellation using any of avariety of modes (e.g. laser, microwave). Various technologies can beused to transmit and receive the broadcasted power. Differingembodiments may be implemented to varying levels of advantage on variousspacecraft sizes, operational requirements (payloads), and spacecraftbus components.

The power receiver module 250 depicted in FIG. 2 is configured toreceive one or more power beams initially transmitted via one or moreother satellites (e.g., a laser beam, microwave beam or some other typeof broadcasted power beam) and convert the power of the received powerbeam(s) into electricity for use by EP system 240 to augment the thrustgenerated thereby, to help charge the batteries 230, and/or to provideelectricity for other purposes of the satellite 200.

The power receiver module 250 includes a beam receiver such as aphotovoltaic array for converting optical power into electricity, arectenna for converting microwave power into electricity, and/or someother type of receiver 252 for converting beamed power into electricity.The power receiver module 250 optionally includes a power conditioner254 suitable for use in conditioning the converted electricity into aform appropriate to the EP system 240 and/or batteries 230.

The power transmitter module 260 depicted in FIG. 2 is configured totransmit one or more power beams toward a target satellite, such as asatellite requiring additional electricity to augment its EP systemthrust capability such as part of an orbital maneuver.

FIG. 3 depicts a flow diagram of a method according to an embodiment.Specifically, the method 300 of FIG. 3 depicts a method of managingpower transfer within a constellation of satellites such as describedherein. The method 300 may be implemented at a ground station managingsome or all of the satellites in a constellation, or at one more of thesatellites within the constellation.

As previously noted, various embodiments provide a mechanism ofequipping an entire constellation of satellites with power beaming andreceiving capability to share power among members of a constellation ofsatellites in conjunction with electric propulsion. One aspect of theembodiments described herein is implementing the power beaming in aconstellation of similarly sized satellites that are all equipped withpower transfer capability and electric propulsion.

At step 310, future target satellite are identified. That is, referringto box 305, future target satellite comprise those satellites having ascheduled EP thrust or other high electricity demand operation, lowbatteries, and need for increased power for payload operation and/orother criteria pertaining to a future need for augmented power on boardthe target satellite.

At step 320, a determination is made for each identified targetsatellite as to the amount of power to be transferred to the targetsatellite and the duration of that power transfer process. That is, adetermination is made as to how much power the target satellite needs toreceive in the form of laser beam, microwave beam and the like, as wellas the start and stop times of transmission of such power. In essence, arequired power profile is determined for each target satellite. Therequired power profile lists power levels and time periods during whichthese power levels should be provided. This may comprise a fixed powerlevel for a fixed amount of time, a varying power level over some periodof time, different power levels at different periods of time and so on.The required power profile for a target satellite may be conceptualizedor defined as total power transmitted to the satellite as a function oftime.

At step 330, for each target satellite a respective group of powersourcing satellite is identified. That is, referring to box 335,membership in the group of power sourcing satellites may be determinedin accordance with line of sight to the target satellite, proximity tothe target satellite, whether or not the batteries of the power sourcingsatellite are charged, the transmit power level capable of beingprovided by the power sourcing satellite, the service life of the powersourcing satellite and/or other criteria.

At step 340, a power beam schedule is generated for each group of powersourcing satellites associated with a target satellite. Specifically,the power beam schedule comprises an identification of power sourcingsatellites selected to provide power for the target satellite at one ormore predetermined times, the amount of power to be provided and so on.The power beam schedule for the group of power sourcing satellitesassociated with a target satellite is configured to cause those powersourcing satellite to provide power beams to their respective targetsatellites in a manner calculated to satisfy the required power profileassociated with the target satellite. It is noted that power sourcingsatellites need not provide power to the target satellite during theentirety of the time period associated with the upcoming power need ofthe target satellite. All that is necessary is that sufficientsatellites at the appropriate times are scheduled to transmit respectivebeams of power (e.g., laser or microwave) toward the target satellitesuch that, in aggregate, the required power profile determined at step320 with respect to the target satellite is achieved.

Generally speaking, a power beam schedule may be determined for a targetsatellite prior to a scheduled high electricity demand operation by thetarget satellite, the power beam schedule comprising at least anidentification of power sourcing satellites selected to provide powerfor the target satellite at one or more predetermined times and anamount of power to be provided by the power sourcing satellites duringthe predetermined times. The predetermined times may comprisepre-operational time periods during which target satellite energystorage levels are increased via received power beam(s), operationaltime periods during which target satellite power used for highelectricity demand operations is augmented by contemporaneously receivedpower beans(s), and/or post-operational time periods during which targetsatellite energy storage levels are restored or otherwise replenishedvia received power beam(s).

Advantageously, the various embodiments described herein provide a stepincrease in spacecraft specific power which enables a defined change inspacecraft orbital velocity to be achieved much more rapidly than withconventional approaches to electric-driven propulsion. FIG. 4graphically depicts time (minutes) as a function of spacecraft specificpower (W/kg) so as to illustrate the benefits of the variousembodiments. For example, a satellite having an electric thruster withconsiderably higher propellant efficiency (Isp, specific impulse) can beused to achieve the delta velocity in a required time due to the higherspacecraft specific power. A highly efficient electric thruster(Isp=1700 sec) coupled with the current invention yields up to a 7×reduction in maneuver time versus prior art coupled with the samethruster.

Further, the various embodiments described herein provide improvedpropellant efficiency which, in turn, translates into increased totaldelta velocity capability of the constellation. Increased total deltavelocity capability enables longer constellation life and/or moreoperational capability. As an example, FIG. 5 depicts a number of 1 m/smaneuvers as a function of spacecraft specific power for an assumed timeand spacecraft propellant mass fraction. It can be seen in FIG. 5 thatthe current invention offers up to a 6.7× increase in the number ofmaneuvers compared to prior EP art for a fixed maneuver time of 6 min.

Further, the various embodiments described herein provide an additionalbenefit in that they enable application of electric thrust at moreoptimal times during orbit transfer maneuvers, which increases theefficiency of propellant use (increases delta velocity capability). Theincreased acceleration potentially enables the spacecraft to accomplishdesired orbit transfers in set prescribed times without continuouslyapplying thrust. The prior art requires electric propulsion thrusting tobe applied continuously to minimize transfer time. The approach requiredby prior art results in a suboptimum use of propellant, and the totaldelta velocity change capability of the satellite is negativelyaffected.

The various embodiments contemplate a constellation of like-sizedsatellites that all have the capability of beaming and receiving power(versus a small number of large power satellites outside of theconstellation that beam power to satellites in another constellationwith only receive capability). Equipping the entire constellation withbeaming and receiving capability increases reliability (resiliency) ofthe constellation. It also operates to decrease costs through economiesof scale.

FIG. 6 depicts a high-level block diagram of a computing device, such asa controller in a satellite, ground station or spacecraft, suitable foruse in performing functions described herein such as those associatedwith the various elements described herein with respect to the figures.

In particular, any of the various functional entities described herein,such as satellites, flight computers, ground stations, communicationsrouting/management entities and so on (and/or portions thereof) asdiscussed within the context of the various embodiments may beimplemented in accordance with a general computing device structure suchas described herein with respect to FIG. 6 .

As depicted in FIG. 6 , computing device 600 includes a processorelement 602 (e.g., a central processing unit (CPU) or other suitableprocessor(s)), a memory 604 (e.g., random access memory (RAM), read onlymemory (ROM), and the like), a cooperating module/process 605, andvarious input/output devices 606 (e.g., communications modules, networkinterface modules, receivers, transmitters and the like).

It will be appreciated that the functions depicted and described hereinmay be implemented in hardware or in a combination of software andhardware, e.g., using a general purpose computer, one or moreapplication specific integrated circuits (ASIC), or any other hardwareequivalents. In one embodiment, the cooperating process 605 can beloaded into memory 604 and executed by processor(s) 602 to implement thefunctions as discussed herein. Thus, cooperating process 605 (includingassociated data) can be stored on a computer readable storage medium,e.g., RAM memory, magnetic or optical drive or diskette, and the like.

It will be appreciated that computing device 600 depicted in FIG. 6provides a general architecture and functionality suitable forimplementing functional elements described herein or portions of thefunctional elements described herein.

It is contemplated that some of the steps discussed herein may beimplemented within hardware, for example, as circuitry that cooperateswith the processor to perform various method steps. Portions of thefunctions/elements described herein may be implemented as a computerprogram product wherein computer instructions, when processed by acomputing device, adapt the operation of the computing device such thatthe methods or techniques described herein are invoked or otherwiseprovided. Instructions for invoking the inventive methods may be storedin tangible and non-transitory computer readable medium such as fixed orremovable media or memory, or stored within a memory within a computingdevice operating according to the instructions.

Various modifications may be made to the systems, methods, apparatus,mechanisms, techniques and portions thereof described herein withrespect to the various figures, such modifications being contemplated asbeing within the scope of the invention. For example, while a specificorder of steps or arrangement of functional elements is presented in thevarious embodiments described herein, various other orders/arrangementsof steps or functional elements may be utilized within the context ofthe various embodiments. Further, while modifications to embodiments maybe discussed individually, various embodiments may use multiplemodifications contemporaneously or in sequence, compound modificationsand the like.

Although various embodiments which incorporate the teachings of thepresent invention have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings. Thus, while the foregoing is directedto various embodiments of the present invention, other and furtherembodiments of the invention may be devised without departing from thebasic scope thereof. As such, the appropriate scope of the invention isto be determined according to the claims.

While the present invention has been illustrated by a description of oneor more embodiments thereof and while these embodiments have beendescribed in considerable detail, they are not intended to restrict orin any way limit the scope of the appended claims to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. The invention in its broader aspects is thereforenot limited to the specific details, representative apparatus andmethod, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thescope of the general inventive concept.

What is claimed is:
 1. A system for sharing power within a constellation of earth orbiting satellites, comprising: a plurality of satellites forming the constellation of earth orbiting satellites, each satellite including a target driven electric propulsion (EP) system and a target power receiver for receiving power beams and converting received power beams into electricity for use by the target EP system to generate thrust, and each of the satellites also including a power transmitter for generating a power beam and transmitting the power beam, whereby each of the satellites forming the constellation of earth orbiting satellites can act as a target satellite and as a power sourcing satellite; when acting as a power sourcing satellite transmitting the power beam toward the target satellite; and when acting as a target satellite, the target satellite being capable of activating both the target EP system to generate EP thrust, and the target power receiver to receive and convert the power beam transmitted by the power sourcing satellite into electricity for use by the target EP system to generate thrust, and thereby augment the EP thrust, whereby power is shared between satellites within the constellation of earth orbiting satellites and the target satellite is maneuvered.
 2. The satellite power sharing system of claim 1, wherein the power beam is comprised of a laser beam.
 3. The satellite power sharing system of claim 1, wherein the target power receiver is comprised of a rectenna.
 4. The satellite power sharing system of claim 1, wherein the power beam is comprised of a microwave power beam.
 5. The satellite power sharing system of claim 1, wherein the target power receiver is comprised of a photovoltaic system.
 6. The satellite power sharing system of claim 1, wherein the EP system is selected form a group consisting of a Hall Effect EP systems, an Ion drive EP system, and an Electrospray EP system.
 7. The satellite power sharing system of claim 1, wherein: the target satellite is comprised of a plurality of the target satellites; the power sourcing satellite is comprised of a plurality of power sourcing satellites; further comprising, a power beam schedule for the each of the target satellites prior to a respective scheduled EP thrust activation or other high electricity demand operation, the power beam schedule identifying for each of the target satellites, one or more power of the power sourcing satellites to provide power for the each of the target satellites; and one or more predetermined time periods for each of the power sourcing satellites to provide power to each of the target satellites.
 8. The satellite power sharing system of claim 7, wherein the power beam schedule further comprises an amount of power for each of the power sourcing satellites to provide during the each of the predetermined time periods.
 9. The satellite power sharing system of claim 7, further comprising: the target satellites having respective energy storage systems and energy levels; wherein, the power beam schedule is calculated to recharge the target satellite energy storage systems prior to the respective EP thrust activations or the other high electricity demand operations, and augment the respective satellite energy levels during the respective EP thrust activations or other high electricity demand operations.
 10. The satellite power sharing system of claim 7, wherein the power beam schedule includes a ranking of the power sourcing satellites according to battery life, expected battery demand, service life, proximity to the target satellites, and power level of the power beam, and also a ranking of the target satellites to provide necessary power to each of the target satellites.
 11. The satellite power sharing system of claim 1, wherein each of the satellites within the constellation of earth orbiting satellites is of similar size and power level.
 12. The satellite power sharing system of claim 1, wherein: the power sourcing satellite is comprised of a plurality of power sourcing satellites; further comprising, a power beam schedule for the target satellite prior to a respective scheduled EP thrust activation or other high electricity demand operation, the power beam schedule identifying one or more power of the power sourcing satellites to provide power for the target satellite; and one or more predetermined time periods for each of the power sourcing satellites to provide power to the target satellite.
 13. The satellite power sharing system of claim 12, wherein the power beam schedule further comprises an amount of power for each of the power sourcing satellites to provide during the each of the one or more predetermined time periods.
 14. The satellite power sharing system of claim 12, further comprising: the target satellite having an energy storage system and an energy level; wherein, the power beam schedule is calculated to recharge the target satellite energy storage system prior to the EP thrust activation or the other high electricity demand operation, and augment the respective satellite energy level during the EP thrust activation or other high electricity demand operation.
 15. The satellite power sharing system of claim 12, wherein the power beam schedule includes a ranking of the power sourcing satellites according to battery life, expected battery demand, service life, proximity to the target satellite, and power level of the power beam. 